Oil-burning engine



June 10, 1930. c. L. cuMMlNs OIL BURNING ENGINE Filed oet. 28, 1927 Patented June 10, 1930 UNITED STATES PATENT OFFICE CLESSIE LYLE CUMMIN S, 0F COLUMBUS, INDIANA, ASSIGNOR TO OIL ENGINE DEVELOP- MENT COMPANY, OF COLUMBUS, INDIANA, A CORPORATION OF INDIANA OIL-BURNIN G ENGINE Application led October 28, 1927. Serial No. 229,400.

This invention relates to oil burning engines and more particularly to means for and method of making such engines more efficient and eliminating carbon troubles. v

I find in oil burning engines where the charge of fuel is injected by an injector into the combustion chamber of the cylinder, that usually the fuel is not thoroughly distributed in the combustion chamber and complete combustion is not accomplished with the following deleterious results: The discharge opening or openings of the injector often become partially and wholl clogged or capped by carbon deposits; cariibn forms adjacent the air inlet and'exhaust valves and interferes with their proper operation; part of the oil charge remains in liquid form and dilutes the lubricating oil in the crank case of the engine; the efliciency of the engine is impaired and best fuel economy is not attained.

The principal object of my present invention is to provide novel means and a novel method for preventing the formation of carbon and affecting better distribution and more perfect combustion of the fuel in the combustion space of oil burning engines, and thus overcome the above objections.

Another object of my invention is to provide improved means for maintaining the fuel injector at the most efficient temperature.

With the above and incidental objects in view, the invention consists of certain novel features of construction and combination of parts, the essential elements whereof are recited in the appended claims, and preferred and modified forms of embodiment of which are described in detail hereinafter and illustrated in full in the accompanying drawings, which form part of this specification.

In the drawings,-Figure 1 is a vertical section taken through the upper part of a fourcycle engine, and shows the preferred form of embodiment of my invention applied thereto;

Fig. 2 is a bottom plan view of the inner cup-shaped member of my injector; and

Fig. 3 is a fragmentary section illustrating a carbon eliminating device of modified form.

Figure 1 illustrates, in section, part of a cylinder head 5, and the upper parts of a cylinder 6 and reciprocating piston 7 of a fourcycle engine of the Cummins type to which for the purpose of illustration, I have shown the preferred form of embodiment of my invention applied, though it will be understood that the invention is equally well adapted for use on oil engines of other types and operated on different cycles. An air intake valve 8 and an exhaust valve 9 may be of any improved construction.

The fuel injector, in general, is similar to that disclosed in my U. S. Patent No. 1,561,913, and may comprise a body member or plug 10, an injecting plunger 11 operable in a central bore 12 of the plug, an inner cup-shaped member 13 fitting over and about the lower end of the plug 10, a second cupshaped member 14 of generally similar shape, fitting over the member 13, a third or outer cup-shaped member 15 fitting over the member 14, and a fuel inlet valve 16 mounted in a bore 17 in the plug 10. The lower end of the cent1-al bore 12 in the plug is closed, except for a small opening 18, by the lower conical end of the cup-shaped member 13, so that when the plunger 11 is retracted or elevated to the position illustrated in Fig. 1 an atomizing or mixing chamber 19 is formed under the plunger. The lower or bottom face of the conical end of the cup 13, as shown in Figs. 1 and 2, is provided with a centrally-located circular protruding portion 21 having grooves 22 therein radiating outwardly from the central opening 18, so thatan annular oil space 23 around the portion 21 and conduit-s formed by the grooves 22 are provided bctwcen the cups 13 and 14. The lower protruding end of the cup 14, is provided with very restricted passages or openings 24 communicating with the combustion chamber 25 of the cylinder. The lower end of the outerA cup 15 is also conical in formation and is provided with a central opening 26 through which the protruding end of the cup 14 extends.

vThe lower end of the fuel inlet valve 16 is pointed and is adapted to close the upper end of a conduit- 27 leading to the annular space 23 formed between the cups 13 and 14. I have not shown in detail in the drawings operating means for actuating the ejecting plunger 11 and the fuel valve 16, as any improved devices may be used. The arms 3() and 31, shown diagrammatically in dotted lines in Fig. 1, may be considered as forming parts of the operating mechanisms for the plunger and valve respectively.

The operation of the injecting mechanism is preferably the same as that described in my aforesaid Patent No. 1,561,913. During the suction stroke of the piston 7, air is drawn into the cylinder past the air inlet valve 8 and during the same stroke the fuel valve 16 is elevated and a charge of fuel iows -through the oil conduit 27, into the annular space 23 and the conduits 22, thus forcing the charge of oil already in said space and conduits into the pointed end of the mixing chamber 19. '1V hile the liquid charge of oil is being deposited in the lower end of the chamber 19 the plunger 11 is slowly elevated. During the compression stroke of the piston, part of the heated air, compressed in the combustion space of the cylinder and heated due to its compression, is forced to flow through the openings 24 and 18 into the chamber 19 Where the oil is entrained and thoroughly mixed with the air. Near the beginning of the power stroke of the piston, the`p1unger 11 is lowered to eject the entire mixture of fuel and air from the chamber 19 through the openings 24 into the combustion space Where the combustible charge is ignited or exploded, thus driving the piston downwardly.

Under some conditions, and particularly v with light fuels, 'I have found that, unless preventive means are provided, the openings 24 become partially or entirely clogged or closed by the formation of carbon, a coating of carbon forms on the lower projecting end of the injector and the surrounding surface of the cylinder head with the result that the intake and exhaust valves do not always seat properly, the charge of oil in the annular chamber 23 and passages 22 are not suficiently heated to permit it to become most eiiieiently vaporized and mixed with the air in the chamber 19. the ejected charge is not most efficiently distributed in the combustion space, and the lubricating oilin the crank case becomes diluted by the fuel which is not consumed by combustion. It is my opinion that when the mixture of air and oil is ejected from the chamber 19 the oxygen in the air in the combustion space immediately around the lower end of the injector is very quickly consumed and the rest of the fuelY and the next oil charge in the annular space 23 and conduits 22 is not heated .as much as desired, carbon forms and is deposited on the lower projecting end of the injector and the adjacent surface on the cylinder head and perfect distribution and mixture of the fuel externally threaded and screwed into the threaded portion of the bore 33. The member 32 is positively locked against rotation on the piston head by means of a lock washer 34 having a lug 35 turned upwardly into a notch 36 formed in a flange or shoulder 37 on the member 32, and a diametrically positioned lug 38 bent downwardly into an opening 39 formed in the pistonhead. .The member 32 together with the lower part of the bore 33 forms an air chamber 4() which is closed except for a nozzle or opening 41 at the upper end of the conical portion of the member 32.

In Fig. 1 the piston 7 is shown at the extreme end of its upstroke. and it will be observed. that the upper end of the member 32 just clears the lower pointed end of the cup 14. During the compression stroke of the piston the pressure in the combustion space increases and part of the air rushes through the opening 41 into the chamber 40, the pressures in the combustion space and chamber 40 being substantially balanced at the end of the compression stroke. As the opening 41 is closely approaching the injecting end of the injector during the end of' compression` stroke it'will be seen that the air rushing through the' opening 41 into the chamber 40 causes some turbulence of the air in the zone around the lower end of the injector. It is also my opinion that when the piston begins its downward movement on the power stroke, the pressure in the combustion space 25 is decreased and the fresh air in the chamber 40 rushes out of the opening 41 feeding -fresh oxygen to the zone around the lowerend of the injector, thus preventing the existence of the zone of poor combustion or over-rich gases. The air rushing through the opening 41 also causes considerable turbulence around the injector and tends to scatter the charge throughout the combustion space with the result that more perfect distribution is accomplished and better combustion is obtained. The air from the chamber 40 also sweeps against the lower end of the injector and tends to carry away any particles of carbon or soot which might form on'it or the surrounding surface on the cylinder head. Thus as the air entering and leaving the chamber 40 causes perfect combustion in the zone adjacent the'lower end of the injector and also sweeps this end clean of carbon deposits, the carbon troubles, heretofore experienced, are eliminated. The eliciency and economy of the engine are greatly increased.

It will be observed that the volume of the chamber 40 is quite small in comparison to that of the combustion space which exists when the piston is at the end of its upstroke as shown 1n Fig. 1. I find that'the volume of the chamber should be less than 10%, and preferably in the neighborhood of 5% of the volume of the combustion space when the piston is in such position. It will also be noted that the cross-sectional area of the casing 32 is relatively small compared with the area of the top of the piston and this is highly desirable for various reasons.

As the zone of poor combustion around the lower end of the injector is eliminated, the lower end of the injector becomes much hotter, due to the increased heat of combustion. I have found that if the cup 15 is not used, the lower end of the injector under some conditions becomes so hot that some of the fuel in the chamber 23 and passages 22 carbonizes and partly clogs them, and burning or breaking down of some of the fuel in the chamber 19, which is objectionable, may take place. The cup 15 acts as a partial insulating shield for the cup 14 and prevents the portion of the cup 14 covered by it from getting too hot. There is a slight space between the lower conical ends of the cups 15 and 14, though this is not essential.

It will be observed that the cup 15 cannot be employed to cover the entire end of the cup 14 due to the necessity of having the communicating openings 24 in the protruding end of the cup 24 which extends through the opening in the cup 15. Therefore, this protruding end of the cup 14 becomes very hot and I have found it advisable to conduct some of the heat away from it in order to prevent carbonization of the oil in the passages 22, and excessive heating of t-he lower end of the chamber 19. To this end I have made the cup 13 of metal, preferably aluminum, having a high co-efiicient of conductivity so that the heat is rapidly transmitted away from the exposed protruding end of the cup 14, which, together with the cup 15 is formed of a metal, such as steel, having a relatively low co-efiicient of conductivity.

In Fig. 3 I have shown a modified form of air chamber 40 provided on the piston. The member 32' is extended downwardly and is screw threaded into an opening in the head of the piston. The lower end of the member 32 may be closed by a plug 44, welded or otherwise hermetically secured to the member 32. The member 32 is prevented from ro tating by means of a pin 42 seated in an openmg in the head of the piston and projectlng into agroove 43 in the projecting fiange of the member 32.

While I have shown and described the preferred form of embodiment of my invention, and also a modified form, it will be obvious that various other changes and modificationsmay be made without departing from the scope and spirit of my invention, as defined in the claims which follow.

I claim:

1. In an oil burning engine, the combination of cylinder having a combustion space and a piston operable in the cylinder, of a fuel injecting device adapted to injt the fuel into the combustion space through communicating means, a recess in the head of the piston and extending below the upper substantially flat portion thereof and a projecting casing on said head and forming a chamber with said recess, an opening being formed in the end of said casing which extends into the combustion space so that at the end of the compression stroke of the piston said opening is in close proximity to said restricted communicating means.

2. In an oil burning en 'ne, having a cylinder provided with a com ustion space and a piston operable in the cylinder, the combination of an injecting device having a discharge portion, a mixing chamber and passage means in the discharge portion to accommodate a charge of oil and conduct a charge of oil to said chamber, means for feeding the charge of oil through said passage means and thereby force the charge already therein into said chamber, means for directing air toward the discharge end 'of said injecting device during the power stroke of the piston and means for partially insulating the discharge portion of the injector from said combustion space.

3. In an oil burning engine, the combination of a cylinder having a combustion space and provided with an opening, a piston operable in said cylinder, a fuel injecting device mounted in said opening, and a heat insulating shield fitted over part of the discharge end of said injecting device, part of the injecting device being formed of metal having a relatively high coeflicient of heat conductivity to carry some of the heat away from that portion of the discharge end of the injecting device not covered by said shield.

4. In an injector for oil burning engines, the combination of a body portion, an 1nner cup on said body portion having a high coeficient of heat conductivity, a second cup around the first cu and having a relatively small coefficient o heat conductivity, said cups having fuel passage means between the same in the discharge end of said injector.

5. In an injector for oil burning engines,

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the combination of a body, an inner cup on said body having a'high coefiicient of heat conductivity, a second cup around the first cup and having a relatively small coefficient of heat conductivity, said cups having fuel passage means between the same in the discharge end of said injector, and a heat insulating shield over part of the discharge end of said injector and means for dischargin substantially fresh air against said shield anl art. Y p 6. -In an internal combustion engine, the combination with a cylinder having a combustion space and a piston operable in said cylinder, of an injectmg device, and an auxiliary air chamber on the piston having an opening so shaped and located as to permit the entrance of air to said chamber from the combustion space and substantially prevent the entrance of fuel to said chamber, substantially fresh air being discharged from said chamber into the combustion space in close proximity to the injecting end of the injecting device, said chamber having a volume less than 10% ofthe volume of the combustion space at the end of the'upstroke of the piston.

7. In an internal combustion engine, the combination with a cylinder having a combustion space and a piston operable therein, of a fuel injecting device 'mounted on the cylinder and having its injecting end exposed to the combustion space and provided with means for directionally injecting the: fuel charge into the combustion space, and an auxiliary chamber having an inlet and outlet opening so situated as to be substantiallyout of ther line of the injected fuel charge, the chamber being supplied with substantially fresh air from the combustion chamber and adapted to cause such air to be directed toward the exposed portion of the injecting device during the power stroke of the piston, the volume of the chamber being less than 10% of the volume of the combustion space at the end of the upstroke of the piston.`

8. In an oil burning engine, the combination with a cylinder having a combustion space and a piston operable in the cylinder, of a fuel injecting vdevice having its injecting end provided with restricted communicating means for injecting the fuel into the combustion space, a relatively small air chamber on the piston for feeding substantially fresh air to the combustion space during the power stroke of the pist-on, the chamber having an opening so' situated with respect to said restricted communicating means as to substantially prevent the entrance of fuel into said chamber and as to be in close proximity to said restricted communicating means at the end of the compression stroke of the piston.

`9. In an internal combustion engine, the combination with a cylinder having a combustion space and a piston operable in said cylinder, of an injecting device', and a relatively small auxiliary air chamber on the iston, means associated wlth the a1r chamer adapted to permit the entrance of a1r to said chamber and substantially prevent the entrance of fuel to the chamber, substantially fresh air being discharged from said chamber into said combustion space in close proximity to the injecting end of the'lnjecting device. v

10. In an oil burning engine, the combination with a cylinder having a combustion space and a piston operable in the cylinder, of a fuel injecting devlce having its injecting end provided with communicating means for injecting the fuel into the combustion space, and a relatively small air chamber on the piston having a tapered end projecting into the combustion space and having a restricted opening located so that only substantially fresh air enters and discharges from said chamber, the opening also being in close proximity to said communicating means at the end of the compression stroke of the piston.

11. In an oil burning engine, the combination of a cylinder having a combustion space and a piston operable in the cylinder, of a fuel injecting device adapted to linject the fuel into the combustion space through communicating means, and an air chamber on the head of the pist-on, the air chamber having a projecting portion extending into said combustion space and provided with an inlet and outlet opening in its projecting end which is in close proximity to but out of alignment with said communicating means at the end of the compression stroke of the piston so that said chamber is supplied with and discharges substantially fresh air, and the cross-sectional area of the air chamber being less than 10% of the area of the top of the piston.

12. In an oil burning engine, the combina- A tion of cylinder having a combustion space and a piston operable in the cylinder, of a fuel injecting device adapted to inject the fuel into the combustion space through rcstricted communicating means, a recess in the head of the piston and a projecting casing on'said head and forming a relatively small chamber with said recess, an opening being formed in the end of said casing which extends into the combustion space so that at the end of the compression stroke of the piston said opening is in close proximity to said restricted communicating means but out of line with the discharge of the fuel charge through said restricted communicating means so that said chamber is charged with and discharges onl substantially fresh air.

13. The met od of preventing the formation of carbon on the injecting end of a fuel injectin space o an oil burning engine, which condevice exposed to the combustion sists in discharging substantially fresh air from a chamber on the piston to the zone of the combustion space immediately around the injecting end of the injecting device while the fuel is being injected into said combustion space by the injecting device, the volume of the air supplied from the chamber being less than 10% of the volume of the air in the combustion space.

14. The method of preventing the formation of carbon on the injecting end of an injector exposed to the combustion space of an oil burning engine and adapted to inject a charge of fuel to thc combustion space, which consists in supplying substantially fresh air from the combustion space to a relatively small reciprocating auxiliary air chamber during the compression stroke of the engine and ejecting substantially fresh air from said auxiliary chamber and in close proximity to the injecting end of the injector during the power stroke of the engine.

15. The method of improving combustion in the combustion space of an oil burning engine around the exposed end of a fuel injecting device, which consists in supplying substantially fresh air from the combustion space to a relatively small auxiliary chamber on the piston of the engine during the compression stroke and discharging the substantially fresh air from the auxiliary chamber to said space during the power stroke of the piston of the engine.

16. In an internal combustion engine, the combination with a cylinder having a combustion space and a piston operable in said cylinder, of an injecting device, and an auxiliary air chamber on the piston having an opening so located as to permitthe entrance of'substantially fresh air to said chamber from the combustion space and substantially prevent entrance of fuel to the chamber and to discharge substantially fresh air to the combustion space in close proximity to the injecting end of the injecting device, said chamber having a volume of approximately j 5% of the volume of the combustion space at the end of the upstroke of the piston.

17. In an oil burning engine, the combination with a cylinder having a combustion space and a piston operable in the cylinder, of a fuel injecting device having its injecting end provided with radiating ports for injecting the fuel into the combustion space, and a relatively small air chamber on the piston for feeding comparatively freshair to the con'ibustion space during the power stroke of the piston and having an opening in close proximity to said projecting end of said device but out of alignment with said ports at the end of the compression stroke of the piston so that substantially no fuel enters said chamber.

18. In an oil burning engine, the combination with a cylinder having a combustion space and a piston operable in the cylinder, of a fuel injecting device for injecting a fuel charge radiatingly through restricted communicating means into the combustion space, and an air chamber projecting from the piston and having a tapered end provided with a small opening in said end, the air chamber also being relatively small compared to the combustion space at the end of the compression stroke and the small opening being adjacent to but out of the line of discharge of said restricted communicating means at the end of the compression stroke of the piston to permit the entrance of air to said chamber and substantially prevent the entrance of fuel thereto.

In testimony whereof, I have subscribed my name.

CLESSIE LYLE CUMMIN S. 

